Power amplifiers can be included in mobile devices to amplify radio frequency (RF) signals for transmission via antennas. For example, in mobile devices using frequency division duplexing (FDD), such as systems using long term evolution (LTE), a power amplifier can be used to provide amplification to one or more transmit carrier frequencies. It can be important to manage RF signal amplification, as a desired transmit power level can depend on how far the user is away from a base station and/or the mobile environment.
The power consumption of a power amplifier can be an important consideration. One technique for reducing power consumption of a power amplifier is envelope tracking, in which a supply voltage of the power amplifier is controlled in relation to the envelope of the RF signal or signal envelope. Thus, when a voltage level of the signal envelope increases the voltage level of the power amplifier supply voltage can be increased. Likewise, when the voltage level of the signal envelope decreases the voltage level of the power amplifier supply voltage can be decreased to reduce power consumption.